The primary objective of this research is to develop an immunogen capable of inducing protection in man against gonorrheal infection. To this end antigen preparations from gonorrheal isolates will be examined to detect components that may be (a) type-specific or (b) associated with virulent isolates. Such an antigen(s) will be purified and, together with other kinds of preparations including formalinized whole cells, pili, sonic extracts and ribosomal fractions, will be used to induce antibody formation in animals and human volunteers. Responses will be monitored by measuring both bactericidal, opsonic and protective activities of the resulting antisera. Secretory IgA and other antibodies specific for N. gonorrhoeae would be sought in secretions of inoculated volunteers and their biologic activity, whether bactericidal or opsonic, would be measured.